The present invention generally relates to nozzles for ink jet printers and their method of manufacture, and particularly concerns the manufacture of nozzle plates having a multiplicity of individual nozzles.
It has been suggested that certain plastics, particularly low surface energy plastics such as polyethylene, polypropylene or fluorinated polymers be employed in the manufacture of nozzles for ink jet printers. See, for example, IBM Technical Disclosure Bulletin 25.8 Jan 1983, p4371. The claimed advantage of using such materials is that the outer face, having a relatively low surface energy, inhibits the spread of aqueous inks in particular. But an associated disadvantage of such nozzle materials is that the ink has an adverse contact angle to and therefore does not wet the surface of the nozzle bore. The suction which draws ink to the exterior surface of the nozzle during operation of the printer is consequently diminished or absent. This suction contributes to ink drop acceleration during ejection of a drop of ink in a drop-on-demand printer and also assists the ink replenishment process which refills the nozzle with ink after printing. For these reasons, nozzles made of low energy polymer are not well suited for use in drop-on-demand printers.
It has been discovered, however, that other plastics, which have not heretofore been proposed for the purpose, are particularly well suited for the manufacture of nozzles for ink jet printers, particularly drop-on-demand ink jet printers. In addition to the selection of an appropriate material, a suitable technology must also be provided to form the nozzles in the material. This technology would preferably be capable of simultaneously forming multiple nozzles in a nozzle plate or the like, wherein the nozzles are in precise registration with the ink ejection channels of the printhead of an ink ejection printer. Laser ablation is a technology particularly well suited for these purposes. The controlled ablation of solid materials using a pulsed UV laser is well known in the art. See, for example, International Application No. 59-154826 which discloses the use of a high energy beam such as a laser to form nozzles in a resin film. Despite this disclosure, the use of lasers in the formation of printhead nozzles is not widely practiced. It is believed that this is at least partially due to the failure of the prior art to disclose techniques for forming ink jet nozzles of appropriate configuration.
It would additionally be highly advantageous to provide a continuous, positive ink flow through the nozzles of a drop-on-demand ink jet printer during printing. Applicants are unaware of any prior art disclosures teaching the use of such positive flow systems.